An optical layered body composed of functional layers having various properties such as an antiglare property, an antireflection property, and an antistatic property is formed on the outermost surface of an image display device such as a cathode ray tube display device (CRT), a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (ELD), a field emission display (FED), a touch panel, or electronic paper.
Such an optical layered body is generally required to have characteristics such as light resistance, that is, UV resistance and oxidation resistance since being set on the outermost surface of an image display device.
Conventionally, in an optical layered body, in order to prevent stains due to deposition of dust or the like because of charge or occurrence of hindrance at the time of use or in the display production process, a resin layer containing an antistatic agent, which is a conductive material, is formed.
Materials known as an antistatic agent to be used for the optical layered body are inorganic materials, e.g., conductive fine particles of metal oxides, for example, antimony-doped tin oxide (ATO), tin-doped indium oxide (ITO), and the like, and carbon (Patent Literatures 1 and 2). However, inorganic materials such as metal oxides have a problem that if the addition amount is large, the light transmittance of an optical layered body is reduced or that the contrast of an image is reduced in the case of installation in an image display device.
Materials also known as the antistatic agent are organic materials such as conductive polymers and quaternary ammonium conductive materials (Patent Literature 2).
Patent Literature 3 discloses an antistatic resin composition characterized by containing a soluble conductive polymer component including a solubilized polymer component having an anionic group and/or an electron-withdrawing group in its molecule and a conductive polymer component, and a hard coat component.
Patent Literature 4 discloses a conductive polymer solution characterized by containing a soluble conductive polymer component including a solubilized polymer component having an unsaturated double bond at the terminal of a side chain of a molecule and a conductive polymer component, as well as a photocurable monomer and/or an organic solvent.
Patent Literature 5 or 6 discloses a conductive polymer/dopant complex-containing organic solvent dispersion containing a conductive polymer, a dopant, as well as a dispersant containing at least one selected from the group consisting of amide compounds or amines having a radical polymerizable group and nonionic surfactants and having a water content of 20 wt. % or less.
However, in the case of using these organic conductive materials and antistatic resin compositions for producing an optical layered body, an optical layered body having a desired antistatic property can be obtained, but it is impossible to obtain an optical layered body which has a sufficiently high contrast of an image while keeping conventional physical characteristics (hard coat property and the like) and optical characteristics (light transmitting property, antiglare property and the like).
Recently, further improvement of the quality of a display image is desired and it is required to realize an optical layered body which can give a higher contrast of an image.
Patent Literatures 5 and 6 disclose usability of polythiophenes as conductive polymers. However, since having no ultraviolet resistance and oxidation resistance, polythiophenes are inconveniently deteriorated in the antistatic property in the case a composition containing polythiophenes is used for producing an optical layered body.